Rushing floodwaters loaded with heavy debris damaged oil and gas pipes and tanks, causing the two large spills that state and federal regulators were tracking Thursday.

Another eight releases, whose cause is undetermined, were classified as minor by the Colorado Oil and Gas Conservation Commission — sheens, for example, coming off of a piece of equipment rather than a measurable volume of petroleum product.

Anadarko Petroleum Corp. on Wednesday reported the two larger releases in Weld County. About 125 barrels — or 5,225 gallons — spilled into the South Platte River near Milliken. A tank farm on the St. Vrain River released 323 barrels — or 13,500 gallons — near Platteville.

Both releases involve condensate — a mixture of oil and water — according to Matthew Allen, a spokesman for the Denver office of the Environmental Protection Agency.

“We are back in the field today looking for ongoing releases,” Allen said. “So far, we haven’t found any of those.”

State law requires oil and gas equipment in the floodplain to be anchored to resist flotation.

The Anadarko tank moorings held, company spokesman John Christiansen said, but strong waters and heavy debris appeared to have cracked pipes and manifolds, allowing the condensate to escape.

Anadarko was able to get absorbent booms and a vacuum truck to the Milliken site and collect about 40 barrels’ worth of the 165 that had spilled, Christiansen said.

But floodwaters kept crews from reaching the tanks on the St. Vrain quickly. “By the time we got there, they were empty,” he said.

The state oil and gas commission is trying to compile a comprehensive list of facilities in the flooded areas and their status, including what chemicals they had on site.

Companies are required by state law to report spills within 24 hours. “But they are moving faster than that with the flood,” said Todd Hartman, a spokesman for the oil and gas commission.

Gov. John Hickenlooper, during a Thursday news conference on flood recovery, said the spills “weren’t excessively large.”

“The several small spills we’ve had have been very small relative to the huge flow of water coming through,” he said.

The Denver Post on Thursday morning flew over the spill site south of Milliken. The site is near the confluence of the St. Vrain and South Platte, which overflowed their banks last week, flooding the towns of Milliken and Johnstown about 5 miles to the north.

From the air, two orange absorbent booms were visible across floodwaters around a cluster of listing beige storage tanks. Less than a quarter-mile away, black material was flowing from a toppled white tank into the muddy waters of the South Platte. There were no booms around that tank.

No industry or state crews were visible at either location.

According to an update Thursday from the oil and gas commission, the state had six teams of inspectors and environmental-protection specialists in the South Platte River valley looking for spills and damage and assessing environmental impact.

A commission staffer also was to fly over the flooded areas with the Weld County Sheriff’s Department.

Anadarko, based in The Woodlands, Texas, is the second-largest operator in the oil-rich Denver-Julesburg Basin, which is centered in Weld County.

There 20,500 operating wells in Weld County, 321 wells in Boulder County, 97 wells in Broomfield County and 253 wells in Larimer County.

Larimer County emergency managers said Thursday they weren’t aware of any spills. “We don’t have the quantity of wells in Larimer County they do in Weld,” sheriff’s spokesman Nick Christensen said.

Anadarko said it has shut 250 tank batteries and 670 wells — about 10 percent of its operations — because of flooding.

The company has deployed about 150 people to check their sites, assess damage and make repairs.

The drilling rigs that the company could move have been transported to sites not affected by the flood. None of the sites where Anadarko is hydrofracturing — pumping large volumes of water, sand and trace chemicals into a well to crack rock and release oil and gas — are in flooded areas, Anadarko’s Christiansen said.

Houston-based Noble Energy reported it has two wells that released natural gas before they were shut during the flood.

“There are no facilities operating under compromise or unknown conditions,” said Tisha Schuller, president of the trade group Colorado Oil and Gas Association.

Wes Wilson, a former EPA environmental engineer who, through Be the Change, leads anti-drilling activists in Colorado, said some of the volatile material leaking into water materials from industry facilities will evaporate quickly.

But the sheens visible on surface water are “an indication of heavy crudes left behind,” he said. Those materials “now will end up in the soil.”

“We are going to have dozens, if not hundreds, of toxic sites,” he said, “and they’ve got to be cleaned up.”

Kevin O’Connor, who lives south of Milliken, said until now he was unaware of how much drilling has been done along the St. Vrain near his home. His main exposure to the industry is the oil- and gas-truck traffic that he encounters commuting to work in Denver.

On Thursday, as he walked over a damaged bridge to look at flood-wrecked vehicles, he said, “There’s no way to plan for an event like this.”

But, he said, the flood has shown that risks are high. “I think we’ve got better ways to create energy,” he said.

Bruce Finley covers environment issues, the land air and water struggles shaping Colorado and the West. Finley grew up in Colorado, graduated from Stanford, then earned masters degrees in international relations as a Fulbright scholar in Britain and in journalism at Northwestern. He is also a lawyer and previously handled international news with on-site reporting in 40 countries.

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